很多深度神经网络模型需要加载预训练过的Vgg参数,比如说:风格迁移、目标检测、图像标注等计算机视觉中常见的任务。那么到底如何加载Vgg模型呢?Vgg文件的参数到底有何意义呢?加载后的模型该如何使用呢?本文将以Vgg19为例子,详细说明Tensorflow如何加载Vgg预训练模型。
实验环境
- GTX1050-ti, cuda9.0
- Window10, Tensorflow 1.12
展示Vgg19构造
import tensorflow as tfimport numpy as np
import scipy.iodata_path = 'model/vgg19.mat' # data_path指下载下来的Vgg19预训练模型的文件地址# 读取Vgg19文件
data = scipy.io.loadmat(data_path)
# 打印Vgg19的数据类型及其组成
print("type: ", type(data))
print("data.keys: ", data.keys())# 得到对应卷积核的矩阵
weights = data['layers'][0]
# 定义Vgg19的组成
layers = ('conv1_1', 'relu1_1', 'conv1_2', 'relu1_2', 'pool1','conv2_1', 'relu2_1', 'conv2_2', 'relu2_2', 'pool2','conv3_1', 'relu3_1', 'conv3_2', 'relu3_2', 'conv3_3','relu3_3', 'conv3_4', 'relu3_4', 'pool3','conv4_1', 'relu4_1', 'conv4_2', 'relu4_2', 'conv4_3','relu4_3', 'conv4_4', 'relu4_4', 'pool4','conv5_1', 'relu5_1', 'conv5_2', 'relu5_2', 'conv5_3','relu5_3', 'conv5_4', 'relu5_4'
)# 打印Vgg19不同卷积层所对应的维度
for i, name in enumerate(layers):kind = name[:4]if kind == 'conv':print("%s: %s" % (name, weights[i][0][0][2][0][0].shape))elif kind == 'relu':print(name)elif kind == 'pool':print(name)代码输出结果如下:
type: <class 'dict'>
data.keys: dict_keys(['__header__', '__version__', '__globals__', 'layers', 'meta'])conv1_1: (3, 3, 3, 64)
relu1_1
conv1_2: (3, 3, 64, 64)
relu1_2
pool1
conv2_1: (3, 3, 64, 128)
relu2_1
conv2_2: (3, 3, 128, 128)
relu2_2
pool2
conv3_1: (3, 3, 128, 256)
relu3_1
conv3_2: (3, 3, 256, 256)
relu3_2
conv3_3: (3, 3, 256, 256)
relu3_3
conv3_4: (3, 3, 256, 256)
relu3_4
pool3
conv4_1: (3, 3, 256, 512)
relu4_1
conv4_2: (3, 3, 512, 512)
relu4_2
conv4_3: (3, 3, 512, 512)
relu4_3
conv4_4: (3, 3, 512, 512)
relu4_4
pool4
conv5_1: (3, 3, 512, 512)
relu5_1
conv5_2: (3, 3, 512, 512)
relu5_2
conv5_3: (3, 3, 512, 512)
relu5_3
conv5_4: (3, 3, 512, 512)
relu5_4
那么Vgg19真实的网络结构是怎么样子的呢,如下图所示:

在本文,主要讨论卷积模块,大家通过对比可以发现,我们打印出来的Vgg19结构及其卷积核的构造的确如论文中给出的Vgg19结构一致。
构建Vgg19模型
def _conv_layer(input, weights, bias):conv = tf.nn.conv2d(input, tf.constant(weights), strides=(1, 1, 1, 1),padding='SAME')return tf.nn.bias_add(conv, bias)def _pool_layer(input):return tf.nn.max_pool(input, ksize=(1, 2, 2, 1), strides=(1, 2, 2, 1),padding='SAME')class VGG19:layers = ('conv1_1', 'relu1_1', 'conv1_2', 'relu1_2', 'pool1','conv2_1', 'relu2_1', 'conv2_2', 'relu2_2', 'pool2','conv3_1', 'relu3_1', 'conv3_2', 'relu3_2', 'conv3_3','relu3_3', 'conv3_4', 'relu3_4', 'pool3','conv4_1', 'relu4_1', 'conv4_2', 'relu4_2', 'conv4_3','relu4_3', 'conv4_4', 'relu4_4', 'pool4','conv5_1', 'relu5_1', 'conv5_2', 'relu5_2', 'conv5_3','relu5_3', 'conv5_4', 'relu5_4')def __init__(self, data_path):data = scipy.io.loadmat(data_path)self.weights = data['layers'][0]def feed_forward(self, input_image, scope=None):# 定义net用来保存模型每一步输出的特征图net = {}current = input_imagewith tf.variable_scope(scope):for i, name in enumerate(self.layers):kind = name[:4]if kind == 'conv':kernels = self.weights[i][0][0][2][0][0]bias = self.weights[i][0][0][2][0][1]kernels = np.transpose(kernels, (1, 0, 2, 3))bias = bias.reshape(-1)current = _conv_layer(current, kernels, bias)elif kind == 'relu':current = tf.nn.relu(current)elif kind == 'pool':current = _pool_layer(current)# 在每一步都保存当前输出的特征图net[name] = currentreturn net
在上面的代码中,我们定义了一个Vgg19的类别专门用来加载Vgg19模型,并且将每一层卷积得到的特征图保存到net中,最后返回这个net,用于代码后续的处理。
测试Vgg19模型
在给出Vgg19的构造模型后,我们下一步就是如何用它,我们的思路如下:
- 加载本地图片
- 定义Vgg19模型,传入本地图片
- 得到返回每一层的特征图
image_path = "data/test.jpg" # 本地的测试图片image_raw = tf.gfile.GFile(image_path, 'rb').read()
# 一定要tf.float(),否则会报错
image_decoded = tf.to_float(tf.image.decode_jpeg(image_raw))# 扩展图片的维度,从三维变成四维,符合Vgg19的输入接口
image_expand_dim = tf.expand_dims(image_decoded, 0)# 定义Vgg19模型
vgg19 = VGG19(data_path)
net = vgg19.feed_forward(image_expand_dim, 'vgg19')
print(net)代码结果如下所示:
{'conv1_1': <tf.Tensor 'vgg19_1/BiasAdd:0' shape=(1, ?, ?, 64) dtype=float32>,'relu1_1': <tf.Tensor 'vgg19_1/Relu:0' shape=(1, ?, ?, 64) dtype=float32>,'conv1_2': <tf.Tensor 'vgg19_1/BiasAdd_1:0' shape=(1, ?, ?, 64) dtype=float32>,'relu1_2': <tf.Tensor 'vgg19_1/Relu_1:0' shape=(1, ?, ?, 64) dtype=float32>,'pool1': <tf.Tensor 'vgg19_1/MaxPool:0' shape=(1, ?, ?, 64) dtype=float32>,'conv2_1': <tf.Tensor 'vgg19_1/BiasAdd_2:0' shape=(1, ?, ?, 128) dtype=float32>,'relu2_1': <tf.Tensor 'vgg19_1/Relu_2:0' shape=(1, ?, ?, 128) dtype=float32>,'conv2_2': <tf.Tensor 'vgg19_1/BiasAdd_3:0' shape=(1, ?, ?, 128) dtype=float32>,'relu2_2': <tf.Tensor 'vgg19_1/Relu_3:0' shape=(1, ?, ?, 128) dtype=float32>,'pool2': <tf.Tensor 'vgg19_1/MaxPool_1:0' shape=(1, ?, ?, 128) dtype=float32>,'conv3_1': <tf.Tensor 'vgg19_1/BiasAdd_4:0' shape=(1, ?, ?, 256) dtype=float32>,'relu3_1': <tf.Tensor 'vgg19_1/Relu_4:0' shape=(1, ?, ?, 256) dtype=float32>,'conv3_2': <tf.Tensor 'vgg19_1/BiasAdd_5:0' shape=(1, ?, ?, 256) dtype=float32>,'relu3_2': <tf.Tensor 'vgg19_1/Relu_5:0' shape=(1, ?, ?, 256) dtype=float32>,'conv3_3': <tf.Tensor 'vgg19_1/BiasAdd_6:0' shape=(1, ?, ?, 256) dtype=float32>,'relu3_3': <tf.Tensor 'vgg19_1/Relu_6:0' shape=(1, ?, ?, 256) dtype=float32>,'conv3_4': <tf.Tensor 'vgg19_1/BiasAdd_7:0' shape=(1, ?, ?, 256) dtype=float32>,'relu3_4': <tf.Tensor 'vgg19_1/Relu_7:0' shape=(1, ?, ?, 256) dtype=float32>,'pool3': <tf.Tensor 'vgg19_1/MaxPool_2:0' shape=(1, ?, ?, 256) dtype=float32>,'conv4_1': <tf.Tensor 'vgg19_1/BiasAdd_8:0' shape=(1, ?, ?, 512) dtype=float32>,'relu4_1': <tf.Tensor 'vgg19_1/Relu_8:0' shape=(1, ?, ?, 512) dtype=float32>,'conv4_2': <tf.Tensor 'vgg19_1/BiasAdd_9:0' shape=(1, ?, ?, 512) dtype=float32>,'relu4_2': <tf.Tensor 'vgg19_1/Relu_9:0' shape=(1, ?, ?, 512) dtype=float32>,'conv4_3': <tf.Tensor 'vgg19_1/BiasAdd_10:0' shape=(1, ?, ?, 512) dtype=float32>,'relu4_3': <tf.Tensor 'vgg19_1/Relu_10:0' shape=(1, ?, ?, 512) dtype=float32>,'conv4_4': <tf.Tensor 'vgg19_1/BiasAdd_11:0' shape=(1, ?, ?, 512) dtype=float32>,'relu4_4': <tf.Tensor 'vgg19_1/Relu_11:0' shape=(1, ?, ?, 512) dtype=float32>,'pool4': <tf.Tensor 'vgg19_1/MaxPool_3:0' shape=(1, ?, ?, 512) dtype=float32>,'conv5_1': <tf.Tensor 'vgg19_1/BiasAdd_12:0' shape=(1, ?, ?, 512) dtype=float32>,'relu5_1': <tf.Tensor 'vgg19_1/Relu_12:0' shape=(1, ?, ?, 512) dtype=float32>,'conv5_2': <tf.Tensor 'vgg19_1/BiasAdd_13:0' shape=(1, ?, ?, 512) dtype=float32>,'relu5_2': <tf.Tensor 'vgg19_1/Relu_13:0' shape=(1, ?, ?, 512) dtype=float32>,'conv5_3': <tf.Tensor 'vgg19_1/BiasAdd_14:0' shape=(1, ?, ?, 512) dtype=float32>,'relu5_3': <tf.Tensor 'vgg19_1/Relu_14:0' shape=(1, ?, ?, 512) dtype=float32>,'conv5_4': <tf.Tensor 'vgg19_1/BiasAdd_15:0' shape=(1, ?, ?, 512) dtype=float32>,'relu5_4': <tf.Tensor 'vgg19_1/Relu_15:0' shape=(1, ?, ?, 512) dtype=float32>}
本文提供的测试代码是完成正确的,已经避免了很多使用Vgg19预训练模型的坑操作,比如:给图片添加维度,转换读取图片的的格式等,为什么这么做的详细原因可参考我的另一篇博客:Tensorflow加载Vgg预训练模型的几个注意事项。
到这里,如何使用tensorflow读取Vgg19模型结束了,若是大家有其他疑惑,可在评论区留言,会定时回答。
备注:本文为作者原创,转载需注明出处!